<?php

defined('BASEPATH') OR exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package		CodeIgniter
 * @author		EllisLab Dev Team
 * @copyright	Copyright (c) 2006 - 2012, EllisLab, Inc.
 * @license		http://codeigniter.com/user_guide/license.html
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */
// ------------------------------------------------------------------------

/**
 * Migration Class
 *
 * All migrations should implement this, forces up() and down() and gives
 * access to the CI super-global.
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Libraries
 * @author		Reactor Engineers
 * @link
 */
class CI_Migration {

  protected $_migration_enabled = FALSE;
  protected $_migration_path = NULL;
  protected $_migration_version = 0;
  protected $_error_string = '';

  public function __construct($config = array()) {
    # Only run this constructor on main library load
    if (get_parent_class($this) !== FALSE) {
      return;
    }

    foreach ($config as $key => $val) {
      $this->{'_' . $key} = $val;
    }

    log_message('debug', 'Migrations class initialized');

    // Are they trying to use migrations while it is disabled?
    if ($this->_migration_enabled !== TRUE) {
      show_error('Migrations has been loaded but is disabled or set up incorrectly.');
    }

    // If not set, set it
    $this->_migration_path == '' AND $this->_migration_path = APPPATH . 'migrations/';

    // Add trailing slash if not set
    $this->_migration_path = rtrim($this->_migration_path, '/') . '/';

    // Load migration language
    $this->lang->load('migration');

    // They'll probably be using dbforge
    $this->load->dbforge();

    // If the migrations table is missing, make it
    if (!$this->db->table_exists('migrations')) {
      $this->dbforge->add_field(array(
          'version' => array('type' => 'INT', 'constraint' => 3),
      ));

      $this->dbforge->create_table('migrations', TRUE);

      $this->db->insert('migrations', array('version' => 0));
    }
  }

  // --------------------------------------------------------------------

  /**
   * Migrate to a schema version
   *
   * Calls each migration step required to get to the schema version of
   * choice
   *
   * @param	int	Target schema version
   * @return	mixed	TRUE if already latest, FALSE if failed, int if upgraded
   */
  public function version($target_version) {
    $start = $current_version = $this->_get_version();
    $stop = $target_version;

    if ($target_version > $current_version) {
      // Moving Up
      ++$start;
      ++$stop;
      $step = 1;
    } else {
      // Moving Down
      $step = -1;
    }

    $method = ($step === 1) ? 'up' : 'down';
    $migrations = array();

    // We now prepare to actually DO the migrations
    // But first let's make sure that everything is the way it should be
    for ($i = $start; $i != $stop; $i += $step) {
      $f = glob(sprintf($this->_migration_path . '%03d_*.php', $i));

      // Only one migration per step is permitted
      if (count($f) > 1) {
        $this->_error_string = sprintf($this->lang->line('migration_multiple_version'), $i);
        return FALSE;
      }

      // Migration step not found
      if (count($f) == 0) {
        // If trying to migrate up to a version greater than the last
        // existing one, migrate to the last one.
        if ($step == 1) {
          break;
        }

        // If trying to migrate down but we're missing a step,
        // something must definitely be wrong.
        $this->_error_string = sprintf($this->lang->line('migration_not_found'), $i);
        return FALSE;
      }

      $file = basename($f[0]);
      $name = basename($f[0], '.php');

      // Filename validations
      if (preg_match('/^\d{3}_(\w+)$/', $name, $match)) {
        $match[1] = strtolower($match[1]);

        // Cannot repeat a migration at different steps
        if (in_array($match[1], $migrations)) {
          $this->_error_string = sprintf($this->lang->line('migration_multiple_version'), $match[1]);
          return FALSE;
        }

        include $f[0];
        $class = 'Migration_' . ucfirst($match[1]);

        if (!class_exists($class)) {
          $this->_error_string = sprintf($this->lang->line('migration_class_doesnt_exist'), $class);
          return FALSE;
        }

        if (!is_callable(array($class, $method))) {
          $this->_error_string = sprintf($this->lang->line('migration_missing_' . $method . '_method'), $class);
          return FALSE;
        }

        $migrations[] = $match[1];
      } else {
        $this->_error_string = sprintf($this->lang->line('migration_invalid_filename'), $file);
        return FALSE;
      }
    }

    log_message('debug', 'Current migration: ' . $current_version);

    $version = $i + ($step == 1 ? -1 : 0);

    // If there is nothing to do so quit
    if ($migrations === array()) {
      return TRUE;
    }

    log_message('debug', 'Migrating from ' . $method . ' to version ' . $version);

    // Loop through the migrations
    foreach ($migrations AS $migration) {
      // Run the migration class
      $class = 'Migration_' . ucfirst(strtolower($migration));
      call_user_func(array(new $class, $method));

      $current_version += $step;
      $this->_update_version($current_version);
    }

    log_message('debug', 'Finished migrating to ' . $current_version);

    return $current_version;
  }

  // --------------------------------------------------------------------

  /**
   * Set's the schema to the latest migration
   *
   * @return	mixed	true if already latest, false if failed, int if upgraded
   */
  public function latest() {
    if (!$migrations = $this->find_migrations()) {
      $this->_error_string = $this->lang->line('migration_none_found');
      return false;
    }

    $last_migration = basename(end($migrations));

    // Calculate the last migration step from existing migration
    // filenames and procceed to the standard version migration
    return $this->version((int) substr($last_migration, 0, 3));
  }

  // --------------------------------------------------------------------

  /**
   * Set's the schema to the migration version set in config
   *
   * @return	mixed	true if already current, false if failed, int if upgraded
   */
  public function current() {
    return $this->version($this->_migration_version);
  }

  // --------------------------------------------------------------------

  /**
   * Error string
   *
   * @return	string	Error message returned as a string
   */
  public function error_string() {
    return $this->_error_string;
  }

  // --------------------------------------------------------------------

  /**
   * Set's the schema to the latest migration
   *
   * @return	mixed	true if already latest, false if failed, int if upgraded
   */
  protected function find_migrations() {
    // Load all *_*.php files in the migrations path
    $files = glob($this->_migration_path . '*_*.php');
    $file_count = count($files);

    for ($i = 0; $i < $file_count; $i++) {
      // Mark wrongly formatted files as false for later filtering
      $name = basename($files[$i], '.php');
      if (!preg_match('/^\d{3}_(\w+)$/', $name)) {
        $files[$i] = FALSE;
      }
    }

    sort($files);
    return $files;
  }

  // --------------------------------------------------------------------

  /**
   * Retrieves current schema version
   *
   * @return	int	Current Migration
   */
  protected function _get_version() {
    $row = $this->db->get('migrations')->row();
    return $row ? $row->version : 0;
  }

  // --------------------------------------------------------------------

  /**
   * Stores the current schema version
   *
   * @param	int	Migration reached
   * @return	bool
   */
  protected function _update_version($migrations) {
    return $this->db->update('migrations', array(
                'version' => $migrations
    ));
  }

  // --------------------------------------------------------------------

  /**
   * Enable the use of CI super-global
   *
   * @param	mixed	$var
   * @return	mixed
   */
  public function __get($var) {
    return get_instance()->$var;
  }

}

/* End of file Migration.php */
/* Location: ./system/libraries/Migration.php */